The invention relates to a rotating electrical machine comprising a stator, a rotor and a turbomachine which is designed for one-sided cooling of the rotating electrical machine, wherein the stator has a laminated stator core, a front stator winding overhang and a rear stator winding overhang and wherein the rotor has a rear rotor winding overhang.
The field of the invention is that of large-scale electrical machines. Because of its slow motor speed, a large-scale machine of this kind, in particular a ring motor of the type used for gearless cement tube mills or also for tube mills for reducing copper ore, must be force-ventilated for cooling purposes. To this end, cooling air is either drawn in from the environment via filters or re-cooled in circulation via air-water coolers. The cooling air flow must be forced through different ducts of the motor using one or more fan-equipped turbomachines powered separately from the ring motor.
Electrical machines having one-sided ventilation, particularly large-scale machines with an output in excess of 10 megawatts and a diameter of more than 5 meters, such as ring motors, are mostly of comparatively simple construction in respect of the routing of airflow. However, because the air becomes heated over the axial length of the machine, the cooling effect diminishes with increasing axial length of the machine, which corresponds to a lengthening of the cooling path. These machines exhibit a temperature gradient which limits their use and can cause thermal stress.
The principle of one-sided ventilation of machines can only be used up to a limited overall length. After that, some other form of ventilation, e.g. two-sided ventilation, has to be used. This requires more overall length. Particularly in the case of machines with large diameters and large ventilation cross-sections, the cooling flow rate also has to be significantly increased in order to achieve approximately the same cooling conditions as with one-sided ventilation of the machine.
JP 60151245 U1 discloses a self-ventilated cooling system in which a fan draws the cooling air through the motor via ducts.